Last time we looked at the amplifier output and found some strange problems. This time we isolate the DSP and verify that in fact, the problem comes from here and is actually worse than previously thought.

 

Now that it’s clear we need to design a replacement DSP, we need to understand all the system level communication going on. With the help of some probes a logic analyzer, a spreadsheet and educated guesswork we managed to do just that.

Files -as promised in the videos- here:

https://www.itsonlyaudio.com/files/HOST TO DSP commands.ods

https://www.itsonlyaudio.com/files/DSS COMMAND MANCHESTER DECODING.ods

https://www.itsonlyaudio.com/files/digital gain vs volume step on RC.ods

The circuit boards for the upgrades have been gathering dust for about a year already. Customers seem to not judge this my highest priority, and fair enough. But fear not, wheels are turning. Next up: upsampling.